ASYNCHRONOUS TO SYNCHRONOUS MODE ON DIE TERMINATION CONTROL CIRCUIT CAPABLE OF GUARANTEEING THE NORMAL OPERATION OF A LATENCY ODT CIRCUIT, AND A METHOD THEREOF

摘要

PURPOSE: An asynchronous to synchronous mode on die termination control circuit and a method thereof are provided to guarantee the normal operation of a latency ODT circuit through a transition to a synchronous mode by satisfying a tXPDLL condition regardless of an operating frequency like an ultra-high frequency and a low frequency.;CONSTITUTION: A DLL part(6) and a DLL replica part(4) generates a DLL output clock by receiving a clock. An ODT control signal output part(80) outputs a ODT control signal by sampling a sync enable signal to the DLL output clock. An asynchronous/synchronous signal generating part(12) generates the asynchronous/synchronous signal according to the logic state of the ODT control signal. A latency ODT circuit(16) changes a mode in response to the synchronous ODT signal. The ODT control signal output part comprises a flip-flop connected over one stage.;COPYRIGHT KIPO 2010